docs: def reduce_sort(self, js_cmp=None, options=None):
          """
          Adds the Javascript built-in ``Riak.reduceSort`` to the query
          as a reduce phase.
  
          :param js_cmp: A Javascript comparator function as specified by
            Array.sort()
          :type js_cmp: string
          :param options: phase options, containing 'language', 'keep'
            flag, and/or 'arg'.
          :type options: dict
          """
          if options is None:
              options = dict()
  
          if js_cmp:
              options['arg'] = js_cmp
  
          return self.reduce("Riak.reduceSort", options=options)